supplement n. something that you add to sth.else to improve it or make it complete The night courses are a supplement to his regular course work. She has been ill and must have supplements to her ordinary food. an additional part at the end of a book,or a separate part of a newspaper,magazine, etc. This history has a supplement containing an account of what has happened since 1930. The newspaper publishes a special travel supplement n. • something that you add to sth. else to improve it or make it complete The night courses are a supplement to his regular course work. She has been ill and must have supplements to her ordinary food. • an additional part at the end of a book, or a separate part of a newspaper, magazine, etc. This history has a supplement containing an account of what has happened since 1930. The newspaper publishes a special travel supplement twice a year